Reproducer for phonographs



March 2, 1937. uc- 2,072,803 I REPRODUCER FOR PHONOGRAPHS Filed Dec. 51,1954 TEFL.

INVENTOR Joseph M L aca relle w, I WW A ORNEYS Patented Mar. 2, 1937UNITED STATES PATENT OFFICE REPRODUCER FOR PHONOGRAPHS ApplicationDecember 31, 1934, Serial No. 759,916

10 Claims.

This invention relates to acoustic reproducers for phonographs and moreparticularly to improved means for modifying the sound transmittedthereby. An object of the invention is to provide an efficientreproducer and modifier device of simple and compact form andconstruction. A further object is to provide a sound modifiereffectively operable gradually to vary tone and intensity of soundtransmitted thereby.

Other objects will be in part obvious and in part pointed outhereinafter.

The invention accordingly consists in the features of construction,combinations of elements and arrangements of parts as will beexemplified in the structure to be hereinafter described and the scopeof the application of which will be indicated in the following claims.

In the accompanying drawing in which is shown one of the variouspossible embodiments of my invention:

' Fig. 1 is an elevation partly in section showing an embodiment of thepresent invention;

Fig. 2 is a plan View of the device shown in (Fig. 1, showing in dottedlines the position of the g5 modifier parts when adjusted for loud soundtransmission; and

Fig. 3 is a cross-section taken on line 33 of Fig. 1 showing themodifier parts adjusted for medium intensity sound transmission.

Similar reference characters refer to similar parts throughout theseveral views of the drawing.

As shown in the accompanying drawing, the carriage IU of a transcribingphonograph is pro- 35 'vided with an opening II in which fits thereproducer and modifier unit, indicated generally by I 2. This unitcomprises a shallow annular sound-box l3 and an upwardly projectingcylinldrical hub I4. The sound-box of the reproducer 40 is provided witha vibratory diaphragm IE to which is connected a link l6 for actuating astylus carrier, not shown, the stylus of which is adapted to track thesound groove of a phonograph record. The vibrations of the diaphragm 45produced by the phonograph record set up in the air chamber ii of thesound-box a succession of sound waves of substantially the samecharacter as those which were recorded on the phonograph record.

In practice it is usual to connect the air chamber of the sound-box bymeans of a passage of relatively small diameter compared with thediameter of the sound-box, with suitable hearing devices adapted tobring the sound waves into 5 effective relation to the ears of alistener; and it has been usual to provide at some point in thetransmission passage means for modifying the sound waves duringtransmission to adapt them to the ears of the listener even though thevibrations transmitted by the diaphragm may include many difierentfrequencies and differ greatly in intensity.

The invention in its illustrated embodiment includes a modifier in theform of a valve member l8 comprising a, cylindrical portion l9,rotatably seated in snug relation to the walls of a cylindrical chamber20, which chamber extends part-way through the hub I4 and is open at theupper end thereof. This chamber is connected to the air chamber I! inthe sound-box by means of an inlet passage 2| of restricted diameterrelatively to the diameter of the air space I l. The cylindrical portionIQ of the valve member is provided with an axial passage 22 ofsubstantially the same diameter as the passage 2|, arranged coaxiallytherewith and forming a direct continuation of the passage 2|. Thispassage 22 extends upwardly into the valve memher a sufiicient distanceto intersect with a radial passage 23 which is adapted to be broughtinto alignment with an outlet passage 24 provided by a tubular member 9extending through the peripheral wall of the hub It. The tubular member9 may be connected in the usual manner with hearing devices by means ofrubber tubing. 7

Before continuing the description, it should be pointed out here thatthe sound passage, constituted by passages 2|, 22, 23 and 24, issubstantially free from enlargements or extensions in the form ofpockets or resonant chambers. The usual practice has been, somewherealong the sound passage to provide a relatively large resonant chamberfrom which, if desired, excess energy could be released by venting tothe atmosphere. It has been found, however, that such resonant chambersshould be avoided since they tend to have a mufiling effect upon thetransmitted sound. In the present structure the sound passage throughoutthe modifier avoids this objectionable feature and other beneficialfeatures have been attained which tend greatly to improve the quality ofsound reproduction.

The valve member I8 is provided at the upper end of the cylindricalportion IS with a cap 25, which, covering the upper end of the hub [4,extends beyond the peripheral walls thereof and provides efficient meansfor rotating the modifier valve. Occupying predetermined angularpositions upon the upper surface of this cap appear the index markingsSoft, Med. and Loud, to indicate the appropriate positions of the valvefor loud, medium or soft sound transmission. These index marks areadapted to be brought respectively into line with a pointer member 26mounted upon the hub l4. Prior to inserting the valve l8 in the hub M, aspring washer 27 is disposed at the bottom of thevalve chamber 20. Thevalve member is then inserted and positioned so that the valve passage23 exactly registers with the outlet passage 24. In this position thespring washer 21' being slightly compressed will offer sufficientresistance to rotation-to maintain the valve in any position of angularadjustment. The

valve is held against axial movement by means ofa screw 28 threadedthrough the wall of hub l4 and having at its inner end a portion adaptedto fit closely between the side walls of an annular groove 29 formed inthe valve cylinder l9.

Stop pins 30 and 3B seated in the groove 29 engage the screw 28'to limitrotation of the valve memberin-one direction at the loud position, andintheopposite direction at the soft position.

Centered in the plane of the horizontal axis of the passage-23 isaV-shaped groove 3|, cut in the peripheral wall of the valve cylinder l9which, starting with a predetermined depth where it intersects the port23-, extends away from the port 23*in-a-counter-clockwise direction andgradually grows shallower until it runs out at a predetermined point"indicated in Fig. 3 by the reference number 32'.

In many sound modifiers it is customary to restrict the passagewaybetween the sound-box and'thehearing devices when it is found desirabletobrin-g the sound waves to the ears of the listener with less'intensity, the restriction of the passage serving to choke back andreduce the energy of the sound wavestransmitted. A certain amount ofrestrictionmay take place without greatly changing the tonal quality ofthe voice sounds received by the listener. However, where very loudsound waves are set up by the diaphragm, since the major portionof theenergy of those sound waves reside in the lower frequency elementsthereof (those below 1,000 cycles), it will happen if the restriction'iscarried far enough that the sounds of low'frequency will predominate. Tooffset this condition, means have'been provided in the presentconstruction-for-providing a variable vent to the outside air, thuspermitting part of the energy of the low frequency sound waves todissipate itself 'exteriorly 'of the sound passage.

Referring to Fig. 3, a vent opening 33 is providedi'n-the wall of thehub M, in the sametransverse plane-as the'groove 3 i and in order toprovide -a passage of variable area connecting the opening;33-with thevalveport 23, a second V- shaped groove 34 isformed in the periphery ofthe valvemember. This groove is shallower than groove 3| and extends inthe opposite direction from the port 23, gradually becoming less deepuntil it'runs out at a poi-ntindicated by 35 in Fig; 3."

Animportant feature of the present invention is thev shaped groove 3|which in the position shown in'Fig. 3 provides an indirect connectionbetweenthe passages 23-and 24. This is approximately the-position thatthe parts would have for mediumdoudness of reproduction. In thisposition-of the parts; in order-for sound to reach the listener, it mustfollow a path making a sharp angle at the beginning-of the groove 3! andanother sharp'angleinto the passage 24'. The efiect produced upon thefrequency characteristics of the sound waves by sharply bending thesound channel is to reduce the high frequency response as the lowerfrequencies tend to mask the higher. But this tendency to mask thehigher frequencies may be compensated by a partial elimination of someof the lower frequency energy. In the present construction this isaccomplished by increasing the effective area of the vent-passage 34 asthe area of the'sound passage 3| becomes more constricted. Thus theV-shaped groove 3| provides a very superior means for accomplishing agradual modification of sound in respect to loudness while theV-shapedgroove 34 by providing an efiicient means for graduallyincreasing the venting as the sound channel is constricted, makespossible the maintaining of a tone of constant quality, whether themodifier be set for loud or soft transmission or at any pointtherebetween.

Thus the present invention provides two marked advantages over modifiersknown to the prior art:one is the construction whereby the passagethrough the modifier is of substantially uniform area, thus eliminatingresonant chambers or pockets; and the other, the means for producinggradual changes in the tone and intensity of the sound received by thelistener as the modifier is changed from one position to another.

A further advantage'ofthe present construction' resides in the fact thatthe modifier comprises a short rotatable annular member mountedcoaxially with respect to the sound passage 2! and sound-box air chamberl1, thus making possible a compact construction, easily adjustable tomeet various conditions of use and of high efiiciency.

It will be seen that there is provided a construction of an essentiallypractical nature in which the several objects of this invention areattained.

As many possible embodiments may be made of the above invention withoutdeparting from the scope thereof, it'is to be understood that all matterherein set forth or shown in the accompanying drawing is to beinterpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In a reproducer, in combination, a soundbox having an upwardlyextending hub, a cylindrical-valve'chamber formed in the upper end ofsaid hub and communicating by means of a coaxial inlet passage with theinterior of said sound-box, an outlet passage extending laterallythrough said hub into communication with said valve chamber, acylindrical modifier valve rotatably mounted in said valve chamberhaving formed therein angularly connecting passages the first of whichis coaxial with and of substantially the same diameter as said inletpassage'and the second of which is of substantially the same diameter assaid outlet-passage and adapted to be brought into registry therewith,said valve having a peripheral groove adapted to connect said'outletpassage with said second valve passage when said passages are moved outof registry with one another, and means for rotating said valve aboutits cylindrical axis.

2. In a reproducer, in combination, a soundbox having an upwardlyextending hub, a cylindrical valve'chamber formed in the upper end ofsaid hub and communicating by means of a coaxial inlet passage with theinterior of said sound-box, an outlet passage extending laterallythrough said hub into communication with said valve chamber, acylindrical modifier valve rotatably mounted in said valve chamberhaving formed therein angularly connecting passages the first of whichis coaxial with and of substantially the same diameter as said inletpassage and the second of which is of substantially the same diameter assaid outlet passage and adapted to be brought into registry therewith,and means for maintaining communication between said outlet passage andsaid second valve passage comprising a peripheral groove in the modifiervalve of gradually decreasing depths.

3. In a sound modifier of the character described, in combination, apair of relatively movable members provided with registrable soundpassages, means for providing gradually decreasing communication betweensaid passages upon further relative movement of said members after theregistrable sound passages have been moved entirely out of registry, andmeans for relatively moving said members.

4. In a sound modifier of the character described, in combination, apair of relatively movable members provided with registrable soundpassages, means for providing gradually decreasing communication betweensaid passages as they are moved out of registry comprising a V-shapedgroove of gradually diminishing depth formed in the contact surface ofone of said members, and means for relatively moving said members.

5. In a sound modifier of the character described, in combination, apair of coaxial relatively rotatable contact members having radiallyaligning sound passages, means for providing gradually varyingcommunication between said passages as they are moved out of alignmentcomprising a groove of gradually varying depth cutting the contactsurface of one of said members, and means for rotating one of saidmembers.

6. In a sound modifier of the character described, in combination, acylindrical valve mem ber containing a sound passage having respectivelyaxial and radial branches, a housing member for said valve member havingan inlet passage in coaxial alignment with said axial branch, and anoutlet passage adapted to communicate directly with'said radial branch,means on one of said members for providing indirect communicationbetween said outlet passage and the sound passage in said valve member,and means for rotating said valve member to render said indirect meansof communication effective.

7. In a sound modifier of the character described, in combination, acylindrical valve member containing a sound passage having respectivelyaxial and radial branches, a housing member for said valve member havingan inlet passage in coaxial alignment with said axial branch and anoutlet passage adapted to communicate directly with said radial branch,means on one of said members for providing indirect communicationbetween said outlet passage and said radial branch, means for rotatingsaid valve member to render said indirect means of communicationeffective, and means for venting said inlet passage to the atmosphere.

8. In a sound modifier of the character described, in combination, acylindrical valve member containing a sound passage having respectivelyaxial and radial branches, a housing member for said valve member havingan inlet passage in coaxial alignment with said axial branch and anoutlet passage adapted to communicate directly with said radial branch,means on one of said members for providing indirect communicationbetween said outlet passage and said radial branch, means for rotatingsaid valve member to render said indirect means of communicationeffective, and means providing a variable vent connecting said inletpassage to the atmosphere.

9. In a sound modifier of the character described, in combination, apair of relatively movable members provided with registrable passages,means for providing gradually decreasing communication between saidpassages as they are moved out of registry, means for simultaneouslyproviding gradually increasing communication between one of saidpassages and the outside atmosphere, both of said means comprising V-shaped grooves of gradually diminishing depth cutting the surface of oneof said members, and means for relatively moving said members.

10. In a sound modifier of the character described, in combination, apair of coaxial relatively rotatable contact members having radiallyaligning sound passages, means for gradually varying communicationbetween said passages as they are moved out of alignment comprising agroove of gradually decreasing sectional area formed in the contactsurface of one of said members, and means for rotating one of saidmembers.

JOSEPH M. LUCARELLE.

